U.S. Pat. No. 6,424,288 invented by Daniel L. Woodell and assigned to the assignee of the present application discloses systems for and methods of displaying radar information using weather radar systems. Weather radar systems generally include an antenna, a receiver/transmitter circuit, a processor, and display. The processor is coupled between the display and the receiver/transmitter circuit. The receiver/transmitter circuit is coupled between the processor and the antenna.
The processor provides transmit signals through the receiver/transmitter circuit to the antenna to transmit radar beams. The processor receives radar return signals derived from radar returns received by the antenna. The radar return signals are provided to the processor via the receiver/transmitter circuit.
Conventionally, pilots use weather radar systems to detect and avoid hazardous weather. The radar return signals are processed to provide graphical images to a radar display. The radar display is typically a color multi-function display (MFD) unit that provides color graphical images to represent the severity and location of weather. Some aircraft weather radar systems also include other hazard detection systems such as a turbulence detection system. The turbulence detection system can provide indications of the presence of turbulence or other hazards. Conventional weather radar systems include those manufactured by Rockwell Collins, Inc., Honeywell International, Inc. and others.
U.S. Pat. No. 6,424,288 discloses an airborne weather radar system that can use multiple scans at different tilt angles to generate a single displayed image. The data from the multiple scans can be compared to reduce visual display of ground clutter. Ground clutter refers to weather radar returns that are the result of reflections from the surface of the Earth or objects associated with the ground. The system can use a measure of power changes between beams at different elevations to determine if weather radar returns are from the ground or weather.
Heretofore, weather radar systems have generally been designed to detect all weather that is in view while removing ground clutter from the display. U.S. Pat. No. 6,603,425 invented by Woodell and assigned to the assignee of the present application discloses such a system. However, such weather radar systems tend to collect and display a large amount of weather images and do not limit the number of weather images provided. Such systems do not necessarily meet customer demands because pilots are more interested in a limited view of weather (e.g., a view of only weather that poses a threat to the aircraft). Although certain weather may be in view, the aircraft's altitude may be such that the detected weather poses no threat to the aircraft because the aircraft flies significantly above such weather. In most situations where weather significance needs to be determined, weather will extend from some maximum altitude to some low level. So in those situations the determination of estimated flight path either penetrating or passing above the weather is required to provide situational awareness. In a few cases, such as the takeoff and climb case, determination of the aircraft's clear path underneath overhanging weather is desired.
Thus, there is a need to determine whether weather is within an aircraft's flight path. There is also a need for a system for and a method of determining presence of weather in a flight path of an aircraft using an on-board weather radar system. Further still, there is a need for real time or pseudo-real time determination of weather that is significant to an aircraft. Yet further, there is a need for a weather radar system optimized to determine the relevant weather. Yet further still, there is a need for a system that automatically rejects weather detection well below an aircraft's current and future position. The need for flight path weather detection can best be seen in light of terminal area operation. In one case a climbing aircraft could be climbing above low altitude weather below the flight path. Detection and display of that non-significant weather would in a best case be a distraction to a flight crew. On the other hand the flight crew of an aircraft beginning a descent into an airport needs to know weather conditions at or near the runway surface. While the display of this weather is very useful during descent, display of this weather during other flight phases could cause the crew to deviate around weather threats that do not exist at their altitude. Even further still, there is a need for a weather radar system that only displays weather that is significant to an aircraft. There is further still a need for a display methodology for such significance (e.g., density modulation for weather under the aircraft's flight path altitude or removal of all weather displays of all weather below the flight path or above the estimated flight path).
It would be desirable to provide a system and/or method that provides one or more of these or other advantageous features. Other features and advantages will be made apparent from the present specification. The teachings disclosed extend to those embodiments which fall within the scope of the appended claims, regardless of whether they accomplish one or more of the aforementioned needs.